CVE-2021-40414 in RLC-410W
Summary
by MITRE • 01/28/2022
An incorrect default permission vulnerability exists in the cgiserver.cgi cgi_check_ability functionality of reolink RLC-410W v3.0.0.136_20121102. The SetMdAlarm API sets the movement detection parameters, giving the ability to set the sensitivity of the camera per a range of hours, and which of the camera spaces to ignore when considering movement detection. Because in cgi_check_ability the SetMdAlarm API does not have a specific case, the user permission will default to 7. This will give non-administrative users the possibility to change the movement detection parameters.
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Analysis
by VulDB Data Team • 02/02/2022
The vulnerability identified as CVE-2021-40414 represents a critical access control flaw within the Reolink RLC-410W security camera firmware version 3.0.0.136_20121102. This issue stems from improper permission handling in the cgi_check_ability functionality of the cgiserver.cgi component, which governs how API requests are authenticated and authorized. The flaw specifically affects the SetMdAlarm API that controls movement detection parameters, including sensitivity settings and ignored camera zones. The vulnerability manifests when the system fails to implement explicit permission checks for this particular API function, resulting in a default permission level being assigned regardless of the user's authentication status or role within the system. This default permission level of 7 effectively grants administrative privileges to any authenticated user, bypassing the intended hierarchical access control mechanisms that should distinguish between standard users and administrators.
The technical implementation of this vulnerability demonstrates a classic case of insufficient authorization checks, which maps directly to CWE-285 - Improper Authorization and aligns with ATT&CK technique T1078 - Valid Accounts. The cgiserver.cgi script processes API requests without properly validating whether the requesting user possesses appropriate privileges for the SetMdAlarm functionality. When the cgi_check_ability function encounters a request for the SetMdAlarm API, it lacks a specific conditional case to handle this particular API call, causing the system to fall back to a default permission level. This default value of 7 provides sufficient privileges to modify critical camera settings including movement detection sensitivity and zone configurations, which are essential components for maintaining security monitoring effectiveness. The vulnerability essentially allows any authenticated user to manipulate the camera's motion detection behavior, potentially enabling attackers to either disable security monitoring or configure false positives that could obscure actual threats.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it fundamentally compromises the security posture of the surveillance system. Non-administrative users who gain access to the camera through legitimate means can now modify movement detection parameters, potentially creating blind spots in security coverage or disabling alerts entirely. This capability undermines the core purpose of security cameras, which is to provide reliable monitoring and alerting services. Attackers could exploit this vulnerability to reduce the effectiveness of security monitoring by adjusting sensitivity levels to ignore critical areas or by configuring detection zones to exclude important locations. The vulnerability also creates opportunities for denial-of-service scenarios where legitimate users might inadvertently or maliciously disable movement detection, leaving the monitored area unsecured. Additionally, the ability to modify detection parameters could be used to create false negatives that mask actual security incidents, making it difficult for security personnel to detect and respond to genuine threats.
Mitigation strategies for this vulnerability should focus on implementing proper access control mechanisms within the firmware code. The most direct approach involves adding explicit permission checks for the SetMdAlarm API within the cgi_check_ability function, ensuring that only users with appropriate administrative privileges can modify movement detection parameters. This aligns with the principle of least privilege and follows security best practices outlined in NIST SP 800-53 and ISO 27001 standards. System administrators should also implement network segmentation to limit access to the camera's administrative interfaces, ensuring that only authorized personnel can reach the camera's API endpoints. Regular firmware updates should be applied to address this vulnerability, and network monitoring should be implemented to detect unusual API access patterns that might indicate exploitation attempts. Organizations should also conduct regular security assessments of their IoT devices to identify similar permission-related vulnerabilities that could compromise their overall security infrastructure. The vulnerability highlights the importance of proper input validation and access control implementation in embedded systems, particularly those handling security-sensitive functions where unauthorized access could have significant operational and security implications.